/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.ipc;

import org.apache.hbase.thirdparty.io.netty.channel.Channel;
import org.apache.hbase.thirdparty.io.netty.channel.EventLoopGroup;
import org.apache.hbase.thirdparty.io.netty.channel.nio.NioEventLoopGroup;
import org.apache.hbase.thirdparty.io.netty.channel.socket.nio.NioSocketChannel;
import org.apache.hbase.thirdparty.io.netty.util.concurrent.DefaultThreadFactory;

import java.io.IOException;
import java.net.SocketAddress;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.HConstants;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hadoop.hbase.client.MetricsConnection;
import org.apache.hadoop.hbase.util.Pair;

/**
 * Netty client for the requests and responses.
 * @since 2.0.0
 */
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
public class NettyRpcClient extends AbstractRpcClient<NettyRpcConnection> {

    final EventLoopGroup group;

    final Class<? extends Channel> channelClass;

    private final boolean shutdownGroupWhenClose;

    public NettyRpcClient(Configuration configuration, String clusterId, SocketAddress localAddress, MetricsConnection metrics) {

        // TODO_MA 注释：
        super(configuration, clusterId, localAddress, metrics);

        // TODO_MA 注释：
        Pair<EventLoopGroup, Class<? extends Channel>> groupAndChannelClass = NettyRpcClientConfigHelper.getEventLoopConfig(conf);
        if(groupAndChannelClass == null) {
            // Use our own EventLoopGroup.
            this.group = new NioEventLoopGroup(0, new DefaultThreadFactory("IPC-NioEventLoopGroup", true, Thread.MAX_PRIORITY));
            this.channelClass = NioSocketChannel.class;
            this.shutdownGroupWhenClose = true;
        } else {
            this.group = groupAndChannelClass.getFirst();
            this.channelClass = groupAndChannelClass.getSecond();
            this.shutdownGroupWhenClose = false;
        }
    }

    /** Used in test only. */
    NettyRpcClient(Configuration configuration) {

        /********
         * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
         *   注释：
         */
        this(configuration, HConstants.CLUSTER_ID_DEFAULT, null, null);
    }

    @Override
    protected NettyRpcConnection createConnection(ConnectionId remoteId) throws IOException {
        return new NettyRpcConnection(this, remoteId);
    }

    @Override
    protected void closeInternal() {
        if(shutdownGroupWhenClose) {
            group.shutdownGracefully();
        }
    }
}
